This invention relates to the discovery and asexual propagation of a new variety of grapevine, Vitis vinifera cv. xe2x80x98Sugratwentythreexe2x80x99. The new variety was first hybridized by David W. Cain in Wasco, Kern County, Calif., the variety being originated by controlled hybridization and subsequent ovule culture of normally abortive seeds. The new variety is characterized by producing naturally large black seedless grapes that are responsive to girdling to increase berry size. The high quality, firm berries are round to ovate in shape, and ripen in midseason.
The seed parent is the xe2x80x98Sun World Breeding Selection 89339-089-291xe2x80x99 (nonpatented) variety and the pollen parent is the xe2x80x98Sun World Breeding Selection 89098-194-167xe2x80x99 (nonpatented). The parent varieties were first crossed in May, 1992, with the date of first flowering being May 1995. The new xe2x80x98Sugratwentythreexe2x80x99 variety was first asexually propagated by David W. Cain in December 1995 in Wasco, Kern County, Calif., using hardwood cuttings.
The new grapevine variety cv. xe2x80x98Sugratwentythreexe2x80x99 most nearly resembles its seed parent, xe2x80x98Sun World Breeding Selection 89339-089-291xe2x80x99. xe2x80x98Sugratwentythreexe2x80x99 differs from its seed parent by having a far superior eating quality. xe2x80x98Sugratwentythreexe2x80x99 produces slightly larger, firmer berries that contain smaller vestigial seed traces, as compared to its maternal parent. The new variety xe2x80x98Sugratwentythreexe2x80x99 differs from its paternal parent, xe2x80x98Sun World Breeding Selection 89098-194-167xe2x80x99 by producing berries that are less prone to cracking and rot. Moreover, xe2x80x98Sugratwentythreexe2x80x99 berries are larger, firmer, and have a later ripening date as compared to the berries of the pollen parent.
The new variety cv. xe2x80x98Sugratwentythreexe2x80x99 distinguished from other commonly grown black grapes such as the xe2x80x98Ribierxe2x80x99 (nonpatented) and the xe2x80x98Summer Royalxe2x80x99 (nonpatented) by several important characteristics.
xe2x80x98Sugratwentythreexe2x80x99 resembles the xe2x80x98Ribierxe2x80x99 variety, but differs from it by having small, soft, vestigial seed traces as compared to the lignified, normal-sized seeds present in the xe2x80x98Ribierxe2x80x99 variety. Additionally, berries of the new variety xe2x80x98Sugratwentythreexe2x80x99 are firmer and have a higher sugar content compared to the berries of the xe2x80x98Ribierxe2x80x99 variety.
The new variety cv. xe2x80x98Sugratwentythreexe2x80x99 also resembles the nonpatented xe2x80x98Summer Royalxe2x80x99 grape variety. It is distinguished from this variety by having larger berries (6 to 8 grams per berry as compared to 4.3 to 5.3 grams per berry in the xe2x80x98Summer Royalxe2x80x99 variety). Berries of the xe2x80x98Sugratwentythreexe2x80x99 variety ripen approximately 1 week earlier than the xe2x80x98Summer Royalxe2x80x99 variety, on clusters that are more compact compared to the xe2x80x98Summer Royalxe2x80x99 variety.
The new xe2x80x98Sugratwentythreexe2x80x99 variety has been shown to maintain its distinguishing characteristics through successive asexual propagations by, for example, cuttings.